1. Technical Field
The present invention relates to a liquid ejecting head and a liquid ejecting apparatus including a piezoelectric element.
2. Related Art
As a liquid ejecting head, there is an ink jet type recording head provided with piezoelectric elements that includes a first electrode, a piezoelectric layer and a second electrode on one surface of the flow channel forming substrate in which a pressure generation chamber linked with a nozzle opening is provided. The ink jet type recording head generates pressure change in the pressure generation chamber by driving piezoelectric elements so that ink droplets are ejected from the nozzle opening. There is a problem in that piezoelectric elements, which are used in the ink jet type recording head, are easily broken due to external environment such as humidity and the like. In order to solve this problem, for example, the second electrode is configured to cover the outer circumferential surface of the piezoelectric layer (for example, see JP-A-2005-88441). The first electrode is a common electrode and the second electrode is an individual electrode in JP-A-2005-88441.
Also, an ink jet type recording head is suggested in which a first electrode of the piezoelectric element is provided in each of pressure generation chambers as a individual electrode and a second electrode is continuously provided in a plurality of pressure generation chambers as a common electrode (for example, see FIGS. 2 and 4 of JP-A-2009-172878). According to the configuration, the second electrode itself serves as a protective film of a lateral surface section of the piezoelectric layer so that there is no necessity to separately provide a protective film.
In the piezoelectric element in which the second electrode is the common electrode as shown in FIGS. 2 and 4 of JP-A-2009-172878, for example, in a piezoelectric body section in which one of upper and lower side electrodes is not present, because there is no electron supply source (electrode) that shields a polarization electric charge that is induced on a piezoelectric body surface by stress deformation, insulation breakage or cracks easily occur by the induced polarization electric charge.
Above-described problem is present not only in the ink jet type recording head but also in the liquid ejecting head that ejects liquid other than ink.